Telephone-circuit



(No Model.) H. VAN HOEVENBERGH.

TELEPHONE CIRCUIT.

No. 300,020. I V Patented Nov, 11, 1884.

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llnrrn TATES a ATENT FFICEO HENRY VAN HOEVENBERGH, OF ELIZABETH, NEIVJERSEY.

TELEPHONE-CIRCUIT.

SPECIFICATION forming part of Letters Patent No. 308,020, dated November11, 1884.

Application filed April 12, 1884.

To all whom, it may concern:

Be it known that I, HENRY VAN Honvmtv BERGH, a citizen of the UnitedStates, residing in Elizabeth, in the county of Union and State of NewJersey, have invented certain new and useful Improvements in Telephone-Oircuits, of which the following is a specification.

My invention relates to the organization of telephonic circuits; and itsobject is to provide means for overcoming the detrimental effects due tothe static capacity of the main line and to induced charges.

Various means have been adopted for preventing or overcoming the staticand induced charges which tend to be present on telephonic main lineswhen those lines are of considerable length. For example, condensershave been employed in such a manner that the charge and discharge of thesame tend to some extent to counteract the effects of the charges, andit has also been proposed to employ various arrangements of metalliccircuits, the direct and return conductors beingso organized thatcurrents traversing extraneous conductors exert little or no detrimentalinfluence.

My invention consists in employing at each terminal of the telephonicconductor an induction-coil, the primary coilbeing included in thecircuit of the mainv line, while the secondary coil is independentlyconnected with the earth, or vice versa. Such an inductioncoil possessesmany of the qualities of, and in many respects is, in effect, acondenser. The transmitting and the receiving instruments are includedin the main-line circuit in the usual manner, preferably at pointsbetween the earth and the coil which is connected with the main line. Byemploying an organization of this character I have found that thedetrimental effects due to static charges upon the line which areotherwise manifest in a telephonic circuit are to a very great extentand in some instances entirely overcome.

In the accompanying drawings, which illustrate my invention, Figure 1'shows a form of induction-coil which I prefer to employ, and Fig. 2illustrates the method of connecting the same in a telephonic circuit.

Referring to the drawings, A represents the core of the induction-coil,which consists of a (No model.)

bundle of soft-iron wires. Surrounding this -core are the two coils, Band B of insulated corresponding contact or switch point, (If

The switch-points (Z are applied to a switch plate, D, and by means of asuitable switchplug, 6, any one'oi the sections maybe connected directlywith the switch-plate through the conductor 0 and point d. This construction is adopted for the purpose of rendering it possible to employ agreater or less number of convolutions of the primary coil in thecircuit of the main line, as desired. When the induction-coils areplaced in the circuit of the main line, it is intended that the mainline shall be connected at its respective terminals with the plates D,as shown in Fig. 2, while the conductors Z,leading to the earth,areconnected with the remaining terminal of the primary coil of theinduction-coil. A plug, 6, is then employed for including as many of thesections of convolutions of the primary coil in the circuit of the mainline as may be desired, and this is accomplished by inserting the plugin one or the other of the holes f between the plate D and the points d.One terminal of the secondary coil B of each induction-coil is connecteddirectly with the earth by conduct ors Z The secondary and primary coilsmay,

if desired, be interchanged with each other as regards theircircuit-connections, the secondary coil being included in themain-linecircuit instead of the primary coil.

The transmitting and receiving instruments are of any well-known form ofconstruction, and they may be included in the circuit of the main lineeither between the induction-coils and the earth or between the mainline and the induction-coils, as found desirable. Usually, however, Iprefer the former organization.

It may in some instances be found desirable to connect both terminals ofthe secondary.

coils with the earth; but usually this is not necessary.

In another application for patent filed by me April 2, 1884, andnumbered 126,422, I have shown and described anorganization of apparatusin many respects similar to that herein shown and described, and I donot therefore herein vclaim anything shown, described, and claimed insaid other application and not specifically claimed herein.

I claim as my invention- 1. The combination, substantially ashereinbefore set forth, of a telephonic main line, a condenser locatedat or near each end of said main line, one arm of each condenser beingconnected with the earth and the other included in the circuit of saidmain line in series, and means for varying the length of the arm whichis thus included in the main line.

2. The combination, substantially as hereinbefore set forth, withtelephonic transmitting and receiving instruments and a main lineuniting the same, of a condenser inserted in said main line at or nearits respective terminals, and having one arm included in circuittherewith, and the other arm connected with the earth, and means,substantially such as described, for varying the static capacities ofthe portions of said condensers included in said main line.

3. The combination, substantially as hereinbefore set forth, with atelephonic main line, of a condenser having the form of an inductioncoilplaced at or near its respective terminals, one coil of each of which isconnected in circuit with the main line and the telephonic instruments,while the other coil is connected directly with the earth.

4. The combination, substantially as hereinbefore set forth, with atelephonic main line, of a condenser having the form of aninductioncoil, the primary coil of which is connected in the circuit ofthe main line together with'the transmitting and receiving instruments,while the remaining coil is connected directly with the earth.

5. The combination, substantially as hereinbefore set forth, of atelephonic main line, a condenser having the form of an inductioncoil,one coil of which is connected with the earth, while the remaining coilis connected in the circuit of the main line together with thetransmitting and receiving instruments, and means, substantially such asdescribed, for varying the number of convolutions of the lastnamed coilwhich are included in series in the main-line circuit.

6. The combination, substantially as hereinbefore set forth, of atelephonic main line, a condenser having the form of an inductioncoilplaced at its respective terminals, one of the coils of saidinduction-coil being connected directly with the earth, while the otheris connected in the circuit of the main line, and means for modifyingthe lengthof the conductor which is included in the circuit of the mainline.

7. The combination, substantially as hereinbefore set forth, of atelephone main line, telephonic instruments connected therewith, and acondenser having the formof an inductioncoil, one coil of which isdivided into sections, in combination with a series of conductorsrespectively leading from such sections, a series of switch-points towhich said conductors lead, and a switch-plate to which saidswitch-points are applied, substantially as described.

In testimony whereof I have hereunto sub scribed my name this 11th dayof April, A. D. 1884.

HENRY VAN I-IOEVENBERGH.

Witnesses:

DANL. W. EDGEooMB, Ormnrns A. TERRY.

